<template>
  <div class="todo-footer" v-show="total">
    <label>
      <!-- <input type="checkbox" :checked="isAll" @change="checkAll"/> -->
      <input type="checkbox" v-model="isAll"/>
    </label>
    <span>
      <span>已完成{{ doneTotal }}</span> / 全部{{ total }}
    </span>
    <button class="btn btn-danger" @click="clearAll">清除已完成任务</button>
  </div>
</template>

<script>
  export default {
    name:'MyFooter',
    props:['todos','checkAllTodo','clearAllTodo'],
    computed: {
      // 总数
      total(){
        return this.todos.length
      },
      // 已完成数
      doneTotal(){
        //此处使用reduce方法做条件统计
        return this.todos.reduce((pre,todo)=> pre + (todo.done ? 1 : 0) ,0)
      },
      // 控制全选框
      isAll:{
        //全选框是否勾选
        get(){
          return this.doneTotal === this.total && this.total > 0
        },
        //isAll被修改时set被调用
        set(value){
          this.checkAllTodo(value)
        }
      }
    },
    methods: {
      /* checkAll(e){
				this.checkAllTodo(e.target.checked)
			} */
      //清空所有已完成
      clearAll(){
        this.clearAllTodo()
      }
    },
  }
</script>

<style scoped>
  /*footer*/
  .todo-footer {height: 40px;line-height: 40px;padding-left: 6px;margin-top: 5px;}
  .todo-footer label {display: inline-block;margin-right: 20px;cursor: pointer;}
  .todo-footer label input {position: relative;top: -1px;vertical-align: middle;
    margin-right: 5px;}
  .todo-footer button {float: right;margin-top: 5px;}
</style>